CRUCIFERAE (MUSTARD FAMILY) 175 
Canada. It is immensely prolific and its seeds have long vitality. 
Cold does it no harm and chemical sprays that kill other 
Mustards do not in the least affect it. Other crops cannot crowd 
it out, for it is the better crowder, seeding in dense timothy sod. 
almost as readily as in a mellow fallow. Blooming “from snow 
to snow” and constantly developing fruit, 
it requires and absorbs much of the food 
and moisture in the soil, starving the ac- 
companying crops almost to worthless- 
ness. T. N. Willing, Chief Weed Inspector 
of the Northwest Territory, says, “It 
will pay well to drop all other work and 
fight this weed when it is first noticed.” 
(Fig. 120.) 
Stem six inches to two feet tall, smooth, 
bright green, often simple but usually 
branching at the top. Root-leaves long 
oval, broadest at tip, with long petioles ; 
stem-leaves lance-shaped and _ clasping 
with a pair of pointed ears at the base; 
all leaves coarsely toothed. When bruised, 
the plant exhales a most disgusting gar- 
licky odor; if it is eaten by milch cows, 
the dairy products are spoiled. Flowers 
clear white, very small, in thick, flat 
terminal clusters; beginning to mature at 
the bottom of the cluster, they leave be- 
hind a long raceme of the fruits, standing 
out on slender, wiry, upcurved pedicels 
about as long as themselves. Silicles flat, 
. Fic. 120.— Penny Cress 
about three-fourths of an inch across, ~ (Tplaspi arvense). Xt. 
pale green at first, broadly winged at the 
sides, notched at the top, two-celled, the division being across 
the narrowest part, as in Shepherd’s Purse; each side contains 
two to eight seeds. As the pods ripen they turn to a rusty 
orange color, making the weed very conspicuous when grow- 
ing with grain or clover. Seeds deep reddish brown, flattened 
ovoid, roughened with fine curved ridges about a central groove. 
